Burnside ordered his pontoon bridges laid at five points on the river. Two bridges were ordered placed across from the north end of town, near the location of the old rope ferry. A single bridge was laid at the south end of town, near a burnt out railroad bridge. Two pontoon bridges were laid a mile south of the middle bridge, near Hamilton Crossing.
Burnside intended to move Sumner's Grand Division across the two bridges of the Upper Crossing and the single Middle Crossing Bridge. Sumner would take the town, and then assault Marye's Heights beyond. While Sumner crossed, Franklin's Grand Division was to move across the southern Lower Crossing. Franklin would assault the Confederates at Hamilton's Crossing and on Prospect Hill, rolling up Lee's line to the north. Hooker's Grand Division would serve as a reserve and feed troops to whichever assault required them. Months after the battle, at a Congressional inquiry, Burnside claimed that Franklin's assault was the key to the entire battle. The first Franklin, or any of Burnside's other subordinates, heard this was at the inquiry.
The Confederate army, of about half as many men as the Union army, sat in wait on the other side of the Rappahannock. Longstreet's corps, which was roughly the size of Sumner's Grand Division, occupied Marye's Heights. Jackson's corps occupied the ground to the right of Longstreet. Jackson's corps had the hardest ground to defend. It was good ground, but not the natural defensive line of Marye's Heights. On Jackson's right flank sat Stuart's cavalry, north of Guinea Station and east of the hills near Hamilton Crossing.
Lee's men were in position to move up or down Telegraph Road wherever Burnside's main thrust hit. To cover the crossings in front of the town, Lee moved a detachment of Brig. Gen. William Barksdale's Mississippi Brigade. The Mississippians and Floridians used the buildings along the waterfront for cover and waited for Burnside's engineers to begin building their bridges.
In the early hours of December 11, the 50th NY Engineers moved down to the river and began laying the bridges. They hoped the darkness would mask their movements, but the noise of the wagons and mules moving down to the river was loud enough to warn the Confederates. More of Barksdale's men moved into place around 4 AM and started sniping at the engineers by 5 AM.
As the sun came up, the Confederates' aim improved. The work was physical and gruelling, as pontoons were placed in the frigid water. The presence of Confederate sharpshooters made it deadly. The engineers were eventually driven off by sniper fire, the men not wishing to risk their lives to assemble the bridge. Union troops fired back but the Rebels were holed up in the buildings and warehouses along the river.
The Union commanders complained about the sniping, and so artillery was ordered to fire on the buildings. A powerful barrage hit the town until 2 p.m. When it lifted, the Confederate snipers fired again, en masse, but not before many had spent hours huddled in rubble without water, while shells fell around them. The crossing had been held up by a small group of Southerners for 8 hours.
The bridges could not be completed while the Confederates fired, and artillery was too imprecise to use as the bridges got further along the river. Until the sharpshooters were suppressed, the bridges couldn't be built. At 2:30 p.m., the 7th Michigan regiment got into boats and rowed to the opposite shore at the Upper Crossing. Fire on the Union troops was intense, but the riverbank was such that the Confederates couldn't fire on them after they got 2/3 of the way across. They landed, formed a skirmish line and pushed back the Confederates holed up along the bank. The 19th Massachussetts arrived at 2:50, followed by the 20th Massachussetts at 3:30. Likewise, the 89th NY landed at the Middle Crossing at 3:15 p.m. After the Confederates were driven back, the engineers completed the bridges.
The fighting in the town was bloody. Every house became a rifle pit. Cul de sacs became death traps. The 20th Massachussetts moved past the hard pressed 19th and the demoralized 7th Michigan. Marching down the streets 4 abreast, fighting house to house, and sometimes only several feet away from the enemy, they took 1/3 casualties. They succeeded, though, in pushing Barksdale's men back through the town. More Union reinforcements moved up.
The 89th NY encountered much the same situation at the Middle Crossing. However, as the Mississippi regiments in front of the New Yorkers withdrew, the 8th Florida regiment was left behind. Surrounded and virtually buried by the earlier artillery barrage, the 8th Florida surrendered.
At the Lower Crossing, Franklin was able to put two bridges across the river virtually unopposed.
As night fell, Barksdale's men were pulled out of the town and moved behind the main line on Marye's Heights. The Union had captured the town.
The next day saw the Union cross the river and build up on the western side. Franklin added a third bridge to the Lower Crossing that was only stable enough to move infantry, but it accelerated his crossing.
In the north, Union troops spent the day cramming into Fredericksburg. They kept a low profile at the western edge of town for fear of bringing down artillery fire. Throughout the town troops looted homes in spite of orders against it. Provost guards, mostly consisting of cavalry, stopped looters escaping with the most obvious of items (such as furniture and rugs) but that didn't stop the town from being picked clean. Fires started near the river, but they were extinguished by Union troops, many of whom were peacetime firemen.
The Confederates spent the day watching the build up. Lee asked Longstreet if if he was worried. Longstreet considered the kill zones set up with infantry and artillery, and was confident that no assault could take the heights. As Colonel Porter Alexander, Longstreet's artillery chief, said to Longstreet, "General, we cover that ground now so well that we will comb it as with a fine-tooth comb. A chicken could not live on that field when we open on it."
Burnside took the time to meet with Reynolds, Smith, and Franklin. His orders to Franklin were to watch his line of retreat, take care while moving in the morning fog, and to take the hills south of Fredericksburg "if possible". His orders to Sumner were more clear; he ordered Sumner to take Marye's Heights. The attack was to commense the next day, but Burnside was late getting the orders out to the grand division commanders. Although written before 6 AM, the formal written orders did not reach Franklin until 7:45 AM on the morning of the attack.
At Antietam Burnside failed to search for other ways to cross the Antietam Creek than by the stone bridge. At Fredericksburg he repeated that mistake by making little effort to reconnoiter Lee's positions. The Union cavalry was mostly wasted in guard duty. The Union failure to use cavalry appropriately was in evidence throughout the campaign. As a result, the Union army marched into battle blind, not realizing how strong the Confederates were on Marye's Heights, or that they were more vulnerable further south.
Burnside's orders to Franklin were less than clear and left a lot to the subordinate general's interpretation. The fog should have been able to shield Franklin's actions, but Burnside's orders could be interpreted as telling Franklin to wait until the fog lifted. The threat to the bridges was real. If left unguarded, Stuart's cavalry would swoop down on them and cut Franklin off with the enemy in front, the river behind, and no way of getting across. However, the orders resulted in Franklin placing an undue weight on the protection of the bridges. The most contentious part of the orders was for Franklin to take the hills around Hamilton's Crossing "if possible" and to attack "with a division at least". Without clear instructions on how much of his command to commit, Franklin chose to interpret the orders as cautiously as possible.
At 8:30 AM, Franklin formed Reynold's First Corps into an attack formation. In the lead was Maj. Gen. George Meade's division. On his right was the division of Brig. Gen. John Gibbon, and between them was the division of Brig. Gen. Abner Doubleday (the man who would later — falsely — claim to have invented baseball). Meade moved forward sometime between 9 AM and 10 AM. The ground he moved over was a plain with ditches and cultivated fields. To the north was Deep Creek, a tributary that ran into the Rappahannock. To the west was a railroad cut, and the wooded Prospect Hill beyond. The Confederates lay in wait in a line along the hills and all the way to Marye's Heights. Stuart's cavalry sat near the road junction south of Prospect Hill known as Hamilton's Crossing.
Meade moved away from the river and westward towards the railroad cut. As he did so, the artillery batteries of Jackson's corps in front of him and Stuart's horse artillery to his left opened fire. Major John Pelham got permission from Stuart to move two of his 18 guns forward with some dismounted cavalry as skirmishers. Pelham fired on the Union soldiers advancing in the fog until Union artillery got his range. He then retreated and commenced firing again. He kept this up for an hour, even after he lost one of the guns. By firing at the Union flank and rear from a range of 400 yards to start with and then retreating when Union gunners got his range, Pelham's efforts impeded Meade's progress towards the railroad cut. It also had the effect of keeping Doubleday's division back in order to protect Meade's flank. Gibbon moved forward with Meade, but his starting position was further east than Meade's, so his division lagged behind that of Meade.
As the fog lifted, Stafford Heights came within sight. The Confederate guns went silent so as not to present a target for the Union guns on the Heights. The Union guns fired blindly towards the Confederate lines but did little damage. Sometime after 11 AM, troops of Stoneman's Third Corps of Hooker's reserve were moved across the river and down the western bank to protect the bridgehead. Reports of troops moving north from Guinea Station (either Stuart's cavalry or CS Maj. Gen. D.H. Hill's infantry division) had filtered through from cavalry pickets, and Franklin moved Stoneman to counter an assault on the bridgehead that never came.
At about noon, Meade and Gibbon advanced on the railroad cut, with Meade's division still in the lead. Confederate artillery opened up on them at 800 yards. Soon after, Union artillery conducted counter-battery fire on the gun flashes of the Confederate artillery. At 1 p.m. Meade's men overran the railroad cut and moved up the slope of Prospect Hill. In front of them were CS Brig. Gen. Maxy Gregg's brigade of Maj. Gen. A. P. Hill's division.
A. P. Hill had made a tactical error on this part of the battlefield. Prospect Hill and the region around it was wooded, but in front was a low, boggy area. A.P. Hill declared this section to be impassible. He kept Gregg behind this area to defend it. To the right and ahead of Gregg was Brig. Gen. James Archer's brigade. To Gregg's left and ahead was Brig. Gen. J.H. Lane's brigade. There was thus a gap consisting of a boggy area and woods between Archer's and Lane's brigades of about 600 yards, with Gregg sitting blindly behind it.
When the Confederate artillery fell silent (except for Pelham, with more of his horse artillery), Meade charged forward, taking heavy Confederate fire from Lane's and Archer's brigades. Reynold's ordered artillery to fire ahead of Meade, and Meade plunged into the woods. The Federals were now in A.P. Hill's "impassable" gap, running uphill but protected from fire by the woods. Ahead of him was an unprepared Confederate brigade.
Doubleday's division remained relatively untouched. When Pelham's artillery was forced to move back from Hamilton's Crossing, Doubleday moved his division towards Meade's left and aimed it to the south. This protected Meade from a flank attack, though there was no immediate threat of one. Meade would have been far better "protected" if Doubleday had been added to the assault. Elsewhere, Franklin moved Smith's Sixth Corps around the bridgehead to protect it. Brigadier John Newton's division was moved south from the bridgehead as additional protection, while Brig. Gen. David Birney's division of Stoneman's corps moved between Meade and the river to defend a road east of the railroad cut.
Meade's men slammed into the flanks of Archer's and Lane's troops anchored in the woods, and pushed into the gap. In front of them, beyond the woods, was CS Brig. Gen. Maxy Gregg's brigade. The Confederates hit by Meade's men broke and ran from the woods. Gregg's troops were so unprepared their guns were still stacked. As Confederates came rushing out of the woods Gregg's men grabbed their guns and fired. Gregg, realizing they were firing on their own men, ordered his troops to hold their fire. The firing slowed and died completely, just as the Union troops boiled out of the woods after the fleeing Confederates. The Federals rushed up the crest of the hill, across the military road, and stormed Gregg's position. Sharp-eyed Northerners saw the General and fired, mortally wounding Gregg. Heavy close quarters fighting ensued and Gregg's line threatened to collapse completely.
Gibbon's division had moved forward with Meade's division, but it fell behind at the railroad cut. As Meade hit the weak spot in Hill's line, Gibbon's division hit Lane's brigade. Unlike Meade, Gibbon moved across relatively open ground. Lane's men were on the edge of the woods and well protected. The Union troops surged forward and engaged the Confederates in hand-to-hand combat. They initially prevailed, but the broken ground disorganized them. Gibbon's attack ground to a halt.
At 1:30 p.m. "Stonewall" Jackson recognized the threat to his Corps and ordered Brigadier Generals William Taliaferro and Jubal Early to move their divisions against Meade and Gibbon. These divisions rushed into the gap and attacked Meade head on. The portions of Archer's and Lane's brigades that had crumbled before Meade formed new lines. Meade's division was now engaged on three sides and taking heavy casualties.
Meade called for reinforcements. None came. Perhaps Franklin was out of touch with what was going on. Perhaps he was simply following too closely Burnside's cautious orders. In any event, Franklin had some 20,000 men in reserve but failed to order any of them forward. Meade had penetrated the Confederate line, but was left unsupported. Low on ammunition and facing a furious onslaught, Meade's men began to withdraw. Soon Gibbon's men did likewise.
Col. Robert Hoke's and Col. Edmund Atkinson's brigades of Early's Confederate Division pursued the Federals. They had been ordered to advance only as far as the railroad cut, but pushed the Union troops even further. They eventually cam into contact with Birney's reserve troops. Low on ammunition themselves and taking cannister fire, they pulled back.
The two sides now found themselves holding the same positions they had earlier in the day. At 2:30 p.m. Burnside ordered Franklin to advance once more, but by this time many of Franklin's officers were demoralized, furious with Franklin for not supporting the breakthrough and thought the situation was hopeless. Franklin, too, was demoralized. He had lost what little faith he had in Burnside and ignored his superior's order to send more men into the battle. "Stonewall" Jackson, on the Confederate side, thought of sending in a counterattack. He ordered a preliminary move by his artillery to support this. A furious response from Union gunners and the waning light convinced him to call off the assault. Franklin had lost 4,830 men killed, wounded, and captured. Jackson's losses were equally severe at 3,415 but he had held off the Union forces in the southern flank of the battle. The battle would now be determined at Marye's Heights.
The men of Couch's Second Corps of Sumner's Right Grand Division stood in columns in the town of Fredericksburg waiting to move forward. Artillery shells crashed around them, unnerving the men and making them anxious to get into battle. They felt that a hotly contested assault was better than standing around defenseless. Before them lay a flat plain, devoid of cover except for a few scattered houses. It was not without obstacles, though. Fences and ditches would slow their progress. A canal lay 200 yards west of the town. The canal could only be crossed at three small bridges, one of which had lost much of its planking. On the other side of the canal, a low bluff offered some small protection. About 350 yards beyond the bluff was an incline that could act as cover for anyone lying flat and hugging the ground. West of the incline was the low ridge of Marye's Heights, 600 yards from the edge of the town.
The Heights were defended by CS Maj. Gen. Lafayette McLaws Division of Longstreet's corps. He placed the Georgia brigade of Brig. Gen. Thomas R. R. Cobb along the sunken road. This consisted of the infantry components of Phillips Legion along the left half of the sunken road, the 18th and 24th Georgia regiments manning the right half, the 16th Georgia guarding the ravine along Hazel Run on the extreme left. Cobb's old command, Cobb's Legion, was understrength and held back as a reserve. McLaws extended Cobb's line 250 yards to the north with the 24th Carolina of Brig. Gen. Robert Ransom's division sitting in trenches. Brig. Gen. Edwin Cooke's brigade of Ransom's division sat on the ridge behind Cobb. McLaws had 2,000 men — 1,000 of which were Cobb's Georgians in the sunken road — defending the ridge, supported by the bulk of Longstreet's artillery, and another 7,000 men behind the ridge in reserve.
The fog lifted at 10 AM, and US Brig. Gen. William French's division began to move forward around noon. Sumner had a habit of leading his men from the front, but Burnside curbed this tendency and ordered him to stay on the east side of the Rappahannock. As the critical assault on Marye's Heights took place, the two senior commanders were on the other side of the river, out of immediate view of the operation.
Artillery ripped into the Union soldiers as they moved across the canal in columns, formed up in battle lines, and advanced on the the Confederate positions. The fire was murderous, a single shell killing or wounding 18 men. In the lead was Brig. Gen. Nathan Kimball's brigade. They queued up to cross the canal at the few bridged points, paused to dismantle a wooden fence in front of them, and then continued the advance, all the while under artillery fire. When they got within 150 yards of the sunken road, the Confederates rose up seemingly out of nowhere. All that could be seen was slouch hats and muskets. An order was given and the muskets were lowered level with the top of the wall. Another order was barely heard as Cobb's men fired a volley into the Yankees. The Southerners dropped below the level of the wall to reload, untouched, while the Federals gave off a ragged counter volley. Some Union men managed to advance to within 40 yards of the Confederates. Others made for the cover of some nearby houses on the right or an unfinished railroad cut on the left. Most, though, reeled at the horrible fire that ripped through them. The wounded and dead collapsed in battle line order while the living tried to exchange fire with the Confederates before making for the cover of the incline. Some of these shots hit their own men, adding "friendly fire" casualties to the bloody devestation. Philips Legion fired "ball and buck" rounds, made up of a mixture of a musket ball and three buckshot. These rounds were inaccurate over any kind of distance, but at the ranges they were engaging the advancing Union soldiers they were horribly effective. Within 20 minutes, a quarter of Kimball's brigade was wounded or dead. Kimball himself was taken off the battlefield severely wounded in the thigh.
French's 3rd Brigade under Col. John W. Andrews came next. The Brigade moved past the incline into the hail of fire. Accounts of the battle repeatedly talk of men moving forward leaning into the torrent of lead as if walking into a driving rain. Fifteen minutes later, half of Andrews' brigade was dead or wounded, with the survivors huddled under the incline. Next came Col. Oliver H. Palmer's brigade, which suffered much the same fate. By about 1 p.m., French's division had 1,153 men killed, missing, or wounded.
As Brig. Gen. Winfield Scott Hancock's division prepared to assault, the Union feared a counterattack. A massive artillery barrage hit the Heights. Meanwhile, the railroad cut and the houses filled with thousands of survivors, many becoming ad hoc sharpshooters. Confederate commanders standing behind the wall and along the more exposed part of the line became targets. There's disagreement about how he was wounded (a nearby soldier said it was from artillery shrapnel, others said from a sharpshooter) but Cobb was hit in the femoral artery. He died of blood loss on the way to a field hospital. Cooke took over command, but he too was wounded. Command passed to Col. Robert McMillan.
The Georgians were almost out of ammunition. Brig. Gen. Joseph Kershaw rode over the top of the hill and into the sunken road. After him came men of his own brigade acting as reinforcements both in men and in ammunition. The 2nd South Carlolina fell in behind Phillips Legion, the 8th South Carolina behind the other Georgians. Ransom moved in his 25th North Carolinians, forming now 6 ranks in the sunken road. These reinforcements paid heavily, as they were the most exposed troops on the hill, first placed above the sunken road and then as they moved down the slope as reinforcements. Likewise, the North Carolinians in the rifle pits north of the sunken road took more casualties than Cobb's men. The six ranks of Confederates fired with excellent coordination, but "friendly fire" casualties still occurred when men in the heights above didn't fire high enough to get the musket balls over Confederates in the row. All told, though, the casualties among the Southerners was nothing like the slaughter among the Northerners before them.
The artillery barrage ended and Hancock's division rushed forward, with Col. Samuel Zook's brigade in the lead. This assault was no more successful than the others. The Confederates held their fire until the Northerners were within close range. Union troops fell as close as 25 yards from the wall. The second brigade in line was Brig. Gen. Thomas Meagher's famous Irish Brigade. Their flags had been shot up previously and were off being repaired, so he had sprigs of boxwood (the closest they could find to shamrocks) placed in their kepis (caps). By coincidence, the men they rushed to meet were Irishmen of McMillan's own 24th Georgia regiment. With regret and pity, they mowed down their fellow Irishmen with murderous fire. Brig. Gen. John Caldwell's brigade followed the Irish Brigade. Two regiments on the left of the line were ordered to shift to the right. This move was done under withering fire within 40 yards of the enemy. The brigade, like the others before it, fell in mass slaughter, the survivors huddled behind the incline.
Couch came to the conclusion that moving his men forward and having them fire on the protected Confederates would not work. The wall protecting the sunken road came up to chest height for the Confederates, while the Union men in front of them were essentially defenseless. Instead, he ordered French and Hancock to make a bayonet charge with their survivors. Climbing to the steeple of the city's courthouse he was horrified at the sight of destruction. It was obvious from there that French and Hancock could not succeed with an assault. At about 2 p.m. he ordered his last division, that of Brig. Gen. Oliver O. Howard, to move to the right of Hancock and French and try to turn the Confederate's left flank. At the same time, Brig. Gen. Samuel Sturgis' division of Wilcox's Sixth Corps was moved forward through the same ground as French and Hancock.
As Brig. Gen. James Nagle's brigade of Sturgis' division fought on the left, Col. Joshua T. Owen of Howard's division moved his own brigade up to the right. He ordered his men to lie down when they got within 100 yards of the wall and to only fire when they had a target. Owen waited for an opening before launching an attack. Owen was supported by the brigade of Col. Nathan J. Hall, and two regiments of Brig. Gen. Alfred Sully, but they made no headway. Back over to their left Sturgis moved in the rest of his division. Likewise, they were unable to get close to the Confederate line.
Hooker did something Burnside did not: he came onto the battlefield and assessed the situation. He became convinced that the frontal assaults would not work, but Burnside dug in his heels and ordered yet another assault. Four divisions had been shattered against the stone wall of the sunken road, but they were not the last. Meanwhile, Couch saw Sturgis' men being cut down on the left. He ordered a battery of artillery to move up to within 150 yards of the wall for support. Men and horses were maimed before some of the guns could even be unlimbered to fire. The few guns that made it did little to affect the outcome.
Some of Hancock's men saw movement on Marye's Heights and erroneously reported that the Confederates were withdrawing. The next assault involved first Brig. Gen. Charles Griffin's division, then Brig. Gen. George Sykes Division, and finally Brig. Gen. Andrew Humphreys' division, all three of Butterfield's Fifth Corps under Hooker. Griffin's division crossed the river at 1 p.m., massed in Fredericksburg at 2 p.m. and was ordered forward at 3 p.m. Confederate fire had not diminished. His men were cut down, as were the men of the trailing divisions, with the demoralized remnants seeking cover below the increasingly crowded incline.
Humphreys had seen what Couch and Hooker had seen, that moving forward to exchange fire with the Confederates would not work. Instead he ordered his men to fix bayonets. They moved out at 5 p.m. and made their way across the canal north of the previous assaults. They charged, angling southwest but they were hampered by the mass of huddled men calling out to them not to go forward, and by the ground littered with the dead and wounded. At 50 yards they were hit by the four lines of Confederates behind the stone wall and were cut down.
Brig. Gen. George Getty's division of Wilcox's Ninth Corps was the last division to advance that day. They moved against the southern section of Marye's Heights, with Col. Rush Hawkins Brigade in the lead. At first the Confederates didn't detect Hawkins' men moving up in the twilight. When they did, they fired at 50 yards and Hawkins' command was shattered. Getty requested support from the men huddled unde the incline, but he was ignored. Getty's men had full knowledge of what went before them and their attack seemed half-hearted. They pulled back with heavy casualties, though they were not as badly bloodied as those that went before them.
Seeing the carnage exacted on Getty and Humphreys, Hooker ended the assaults. He later observed that he had "lost as many men as his orders required". Sumner and Hooker had lost about 7,817 men killed, wounded, or missing. In comparison, Longstreet reported that he had 1,893 casualties, most of these coming from Kershaw's brigade and Ransom's division. Added to the casualties on Franklin's front, the Union had lost 12,535 casualties to about 5,000 on the Confederates' side. Earlier in the day, Lee had viewed the battle from Telegraph Hill (later called Lee's Hill) when he made his famous remark, "It is well that war is so terrible — we should grow too fond of it." Sergeant Montgomery of Phillips Legion, who saw more combat than any other man in that regiment, admitted, "I never saw in my life such a slaughter." One survivor of the 18th Pennsylvania said, "It was simply murder!"
Burnside visited units that night, his demeanor cheerful. But it was obvious to Couch that this was a front. Burnside blamed himself for the disaster. He announced that night that the Ninth Corps would conduct an assault at dawn and that he would lead it personally. It was a suicidal attack, and that was its intention. Burnside would either succeed in taking the Heights or die trying. Before dawn, as the Corps prepared for the assault, Sumner went to Burnside and strongly denounced the assault. Burnside met with his commanders and was convinced not to renew the fighting. Instead, he made plans to pull his men off the battlefield. The Second and Fifth Corps would hold the town, giving them something to show for the carnage.
The temperature dropped and was bitterly cold that night. The Union dead, wounded, and living lay on the battlefield below the Heights. The cold created more casualties as the night wore on, particularly against the more exposed Federals. Confederates sniped at the cowering Northerners, many of whom stacked frozen corpses near them to act as protective bulwarks. Stretcher bearers moved amongst the troops during the day. At night scavenging soldiers moved among the dead. Confederates who tried to take overcoats from dead Federals complained that the buck and ball rounds had left too many holes. The moaning of the wounded and dying was constant. The situation was essentially stalemated throughout the night of the 13th and on through the 14th of December. On the 14th a Confederate soldier, Sgt. Kirkland of the 2nd South Carolina, moved over the wall. At great risk to his life, he brought water and aid to Northern and Southern wounded, alike, earning him the nickname of the Angel of Marye's Heights.
A truce was arranged on the 15th and wounded from both sides were pulled from the battlefield. A driving rain hit on that day. Under its cover, the Union army withdrew. Burnside had a change of heart and ordered the Second and Fifth Corps to abandon the town. Dirt and straw muffled their movement over the pontoon bridges. On the morning of the 16th the Confederates were surprised to see that the Army of the Potomac had retreated completely.